Boiler-plug.



- partly in elevation.

UNITED STATES PATENT OFFICE,

EUGENE J. MCCABTY, 0F CLINTON, MASSACHUSETTS, ASSIGNOR TO MAX MACHINECOMPANY, OF CLINTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

BOITIER-PLUG.

Speicicaton of Letters Patent.

Patented J une 23,1914.

I. Application filed April 3, 1911. Serial No. 618,525.

To all whom yit lm ay conce/rn:

Be it known that I, EUGENE J. MoCiiirrY, a citizen of the United States,residing at Clinton, in the county of Worcester and State ofMassachusetts, have invented new and useful Improvements inBoiler-Plugs, oi' which the following is a specification.

My invention relates to boiler plugs, and its objects are to provide aneil'ective means of closure for the ends of boiler tubes or dues, and toprevent the blowing out of Said closure means under the conditions ofactual ilse. v

My invention consists in constructing a boiler-plug in the form of a cupshaped disk, the walls of which are concaved or taper outwardly for thepurpose of permitting the plug tobe readily introduced within a boilertube normally of a slightly smaller interior diameter than the largestexterior diameter of the plug.

My invention further consists in the improvements and novel arrangementopai'ts more particularly hereinafter pointed out and claimed.

Attention is hereby7 directed tothe d rawing in which similar numeralsof designation refer to similar parts throughout the several views.

Figure l is a horizontal section of myimproved plugafter it has beenduly installed, showing the boiler tube partly in section and Fig. 2 isa section sinnlar to Fig. 1, but showing in an exaggerated. forni` forthe purposes of illustration, the annular groove in the wall of the-plugbefore it has been expanded into the positionl shown in" Fig. l.

Referring to the drawing; the plug 3 is composed ot' metal, and may berolled, turned, cut, or cast in the form here shown. In the wall 4 ofthe plug is an annular recess which is extremelyy shallow, andl ispreferably concave. My primary purpose in having this recess is toprevent any portion of the wall 4 Jfrom coiningin Contact with theboiler tube while plug is being installed except the portions 6 andv 7,which when both are at the same vtemperature are slightly greater indiameter than the interior diameter of the boiler tube 8. Preferablythis difference in diameter is the exact depth of the recess 5.

I prefer. to introduce my plug While cold into the end of the boilertube 8 while the same i s hot, preferably while it is still under theinfluence of the steam of the boiler while iny use in order that when myplug expands with lthe heat, the walls ot' the plug and tube will com@int() Close contact and the recess 5 will be eliminated as shown in Fig.l. To accomplish this result, itis necessary that the annulairecess beof merely sufficient depth to just prevent the said walls fromtouching,-`-a microscopic variation being all k that is i'iecessaiy ordesirable. Such propor` tions are Inot readily observa-ble with thenaked eve, and would exist within the width of the line of separationor' tliewalls shown in Fig. l; the exaggerated recess 5` shown in Fig.for the purposes of illustration not being desirable in my preferredform of construction, though within the scopel of my invention. Thismethod of construct-ion differs essentially from shrinking, as the term'is commonly used, since theplug is designed to be introduced not onlywhen the boiler is being made but also after the same has been piitiintoactual use; the heat produced by the boiler being sufficient for @HUS-ing the walls of in v plug and tube to come.' in Contact upon theexpanding ot' the material of which the plug is composed.

In some cases it may be`fouiid convenient to construct my plug taperingoutwardly, that is, with the diameter of the plug be- Icoming graduali)7smaller away from the portion 3. But in such ease care should bc takento have the 'taper ot' the same microscopic dimensions as that ot' theannular recess 5 above described in order that the walls may just clearwhen the plug is first installed in position. Since it is my purpose inthe preferred form of my invention merely to have sufficient ot' thesurface ot' the plug to come iii contact with the tube in order that.the two may be wedged together without splitting the tube, and to haveall other parts vot' the wall ot thel plug .separated iii the slightestdegree from ,the wall of the tube while installation is taking place, Idesire to include as within uiy invention any form of plug embodyingthese features no mattei' how the recesses are formed or situated.

Through the use of my improved construction, I am able at an instantsnotice to install one of my plugs in any boiler tube even where anoldform of plug has been used. In the construction now on the market it iscommon practice to use plugs which are cast-- solid and driven into thetube without expanding; Such a method of connection is objectionable forthe reason that it is hard to make a tight joint and is liable to blowout. Since my plugs are all made in standard sizes with expansion metalthey may be rolled or expanded with a tool ot' the same style as is usedto roll or expand the tubes and thus form a greater diameter back of theboiler head by outward pressure on thel tube; it would then beimpossible with very high hydraulic pressure to start these plugsyslstng in inserting the plugwhile cold into a the tube while the tube isexpanded by heat and keepingthe tube heated until the plug has becomeheated to the same temperature as the tube, the plug having a pluralityof diameters, the inner one of which when cold lits the bore of theheated tube with a wedgl ing lit and the outer end of which when cold isminutely smaller than the bore ot' the heated tube, whereby when it thusbecomes heated to a temperature equal to that of the tube it Will havebecome expanded sufficiently to cause it to become permanently locked in'the tube and have a continuous contact with the inner face of the tubethroughout its outer or peripheral surface.

2. The method herein described of plugging the ends of boiler tubesconsisting in inserting the plug while cold into the tube While the tubeis expanded by heat and keeping the tube heated until the plug has belcome heated to the same temperature as the tube, the diameter of theplug at its inner end being such that when thus inserted in a cold stateit will have a wedging fit in the bore of the heated tube while thediameter of the plug throughout the larger part of its length isminutely less than the interior diameter of the tube, whereby when itthus becomes heated to a temperature equal to that ot' the. tube it willhave become expanded sufficiently to cause it to become permanentlylocked in the tube and have a continuous contact with the inner face ofthe tube throughout itsI outer or peripheral surface.

3. The method herein described of plugging the ends ot' cylindricalboiler tubes consisting in inserting a hollow plug while cold iuto thetube while the tube is expanded by heat and keeping the tube heateduntil the plug has become heated to the same temperature as the tube,the diameter of the plug at its outer and inner ends being such thatwhen it thus becomes heated to a temperature equal to that of the tubesaid outer and inner ends will hare become expanded sulticiently tocause it to become permanently locked in the tube, and the diameter ofthe plug intermediate said ends being minutely less than at said ends.

ln testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses, this 30th day of March, 1911.

EUGENE J. BCCARTY.

1Witnesses:

THOMAS J. MCNAMARA, lYiLLIAM H. DIETZMAN.

